JP2016201664A - Packet relay device and band control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packet relay device and a bandwidth control method capable of bandwidth control in which the amount of information to be notified is reduced. A packet relay device has a plurality of band control units that control the bands of passing packets, and the plurality of band control units are each supplied at a constant rate and subtracted by passing the packet. A passage control unit that determines whether or not a packet can pass based on the passage allowance and passes or discards the packet according to the determination result, and a plurality of band control units that measure the packet passage amount at regular intervals. Of these, the pass amount management that notifies the other band control unit of the numerical value of the upper digit of the pass amount and inherits the numerical value of the lower digit of the pass amount to the pass amount to be measured in the next period. The unit, the passage amount acquisition unit for obtaining the provisional passage amount by returning the numerical value of the upper digit notified from the other band control unit to the digit, and the provisional passage amount are subtracted from the passage allowance. It has a passage allowance management unit. [Selection diagram] FIG. 9

Description

  The present case relates to a packet relay device and a bandwidth control method.

  A packet relay apparatus that relays packets includes a plurality of policers having a policing function for each interface card (hereinafter referred to as “IF card”) that processes transmission and reception of packets. The policer passes a packet by consuming tokens supplied at a constant policing rate, and controls the bandwidth of the packet passing through the packet relay device by discarding the packet when the tokens are insufficient (for example, patents). Reference 1).

JP 2013-197823 A

  The policer controls the bandwidth for each user traffic identified by a VID (VLAN (Virtual Local Area Network) Identifier) or MPLS (Multi-Protocol Label Switching) label of the packet. For this reason, the token supply rate of each policer, that is, the policing rate, is determined according to the bandwidth contracted by the user.

  For example, in order to improve the apparent communication speed, when link aggregation (Link Aggregation) that bundles multiple links (physical communication lines) is used, multiple policers installed on different IF cards can receive the same user. Traffic packets may be input. In this case, a plurality of policers are grouped, and every policer belonging to the group passes the packet, and all policer tokens are consumed.

  This makes it possible to limit the total bandwidth of the traffic of the same user input over a plurality of policers as a whole. This bandwidth control method (hereinafter referred to as “group policing”) may be performed for a group of a plurality of policers into which different user traffic packets are respectively input.

  In group policing, each policer belonging to the same group measures the amount of data of a packet that has passed through the policer, that is, the amount of passage, at regular intervals and notifies the policer of another IF card. Each policer subtracts the passing amount notified from the policer of the other IF card from the token of the policer.

  For this reason, as the policing rate and the number of policers increase, the amount of information transmitted / received between policers of different IF cards increases. Therefore, each IF card has a large-scale hardware equipped with a transfer capability corresponding to the amount of information. Is required.

  For example, if the policing rate is 100 (Gb / s) and the period of notification of the passing amount is 10 (ms), the maximum data amount of packets passing within 10 (ms) is 125 (MByte) (= 100 ÷ 8 × 0.01). Therefore, the amount of information necessary for notification of the passage amount is 27 (bits) when converted to a binary number.

  Therefore, when the number of policers mounted on one IF card is 100,000, the transmission rate required for the IF card is 270 (Mb / s) (= 27 × 100K ÷ 0.01). If group policing is performed between four IF cards, the reception rate required for each IF card is 1.08 (Gb / s) (= 270 × 4). Therefore, each IF card requires a gigabit rate data transfer capability in addition to the main signal packet. Note that when the IF card notifies the amount of passage for each policer with an individual packet, the amount of information transmitted / received increases, and thus higher transfer capability is required.

  For example, when the period of notification of the passing amount is shortened to 1 (ms), the maximum data amount of packets passing within 1 (ms) is 12.5 (MByte) (= 100 ÷ 8 × 0.001). It is. Therefore, the amount of information necessary for notification of the passing amount is 21 (bits) (<27 (bits)) when converted to a binary number.

  On the other hand, for example, when the period of notification of the passage amount is extended to 100 (ms), the maximum data amount of packets passing within 100 (ms) is 1.25 (GBe) (= 100 ÷ 8 × 0.1) It is. Therefore, the amount of information necessary for notification of the passing amount is 31 (bit) (> 27 (bit)) when converted into a binary number.

  Thus, if the time interval for notifying the passing amount is shortened, the amount of information transmitted and received in one notification is reduced, but the frequency of notification increases, while if the time interval for notifying the passing amount is increased, the notification is performed. However, the amount of information transmitted and received in one notification increases. Therefore, the IF card requires a high transfer capability regardless of the time interval for notifying the passing amount.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a packet relay apparatus and a bandwidth control method capable of bandwidth control with a reduced amount of information to be notified.

  The packet relay device described in this specification has a plurality of bandwidth control units that respectively control the bandwidths of the packets that pass through, and each of the plurality of bandwidth control units is supplied at a constant rate and is subtracted by the passage of the packets. A pass control unit that determines whether or not a packet is allowed to pass based on an allowed passing amount, and passes or discards the packet according to the determination result, and measures a packet passing amount for each predetermined period, and the plurality of bands Among the control units, notify the other band control unit of the numerical value of the higher-order digit of the passing amount, and pass the numerical value of the lower-order digit of the passing amount to the passing amount measured in the next period An amount management unit, a passage amount acquisition unit that obtains a provisional passage amount by returning the numerical value of the higher-order digit notified from the other band control unit to the digit, and the provisional passage amount from the passage allowance amount Allowable passage amount to be subtracted And a processing section.

  The bandwidth control method described in the present specification is a bandwidth control method for controlling the bandwidth of a packet that passes through a plurality of bandwidth controllers, wherein each of the plurality of bandwidth controllers is supplied at a constant rate and passes packets. A plurality of bandwidth control units that determine whether or not a packet is allowed to pass based on a permissible passing amount subtracted by the step, and pass or discard the packet according to the determination result, and measure a packet passing amount at regular intervals, Among them, it notifies the other band control unit of the numerical value of the higher-order digit of the passing amount, takes over the numerical value of the lower-order digit of the passing amount to the passing amount measured in the next period, The provisional passage amount is obtained by returning the numerical value of the higher-order digit notified from the band control unit to the digit, and the provisional passage amount is subtracted from the allowable passage amount.

  Band control with a reduced amount of information to be notified becomes possible.

It is a block diagram which shows an example of a packet relay apparatus. It is a block diagram which shows an example of an interface card. It is a figure which shows the path | route of the packet in a packet relay apparatus. It is a block diagram which shows an example of a zone | band control part. It is a figure which shows an example of a token management table. It is a flowchart which shows an example of a process of a token management part. It is a flowchart which shows an example of a process of a policing part. It is a figure which shows an example of the interface card which comprises a policing group. It is a figure which shows an example of the notification process of the passage amount. It is a flowchart which shows an example of a process of the passage amount notification part. It is a flowchart which shows an example of a process of a passage amount receiving part. It is a figure which shows an example of a process of a passage amount management table and a temporary passage amount management table. It is a graph which shows an example of the change of the passage amount and temporary passage amount for every period. It is a figure which shows the other example of a process of a passage amount management table and a temporary passage amount management table. It is a figure which shows the other example of the notification process of the passage amount. It is a figure which shows an example of band control. It is a graph which shows the simulation result of the output rate in a comparative example. It is a graph which shows the simulation result of the output rate in an Example.

  FIG. 1 is a configuration diagram illustrating an example of a packet relay device. The packet relay apparatus includes a plurality of interface cards (IF cards) 91, two switch cards 92, and a control card 93. Each of the cards 91 to 93 is housed in an individual slot provided in the housing and is electrically connected to each other. Examples of the packet relay device include a layer 2 switch and a router.

  The packet relay device relays the packet received from the other device to the other device according to the destination. In this embodiment, a packet is a transmission unit (PDU: Protocol Data Unit) of data (information) to be transmitted, and an Ethernet (registered trademark, the same applies hereinafter) frame is given as an example, but is not limited thereto. Other PDUs such as IP (Internet Protocol) packets may be used.

  Each of the plurality of IF cards 91 transmits / receives a packet to / from another device. Examples of the other device include a terminal device such as a personal computer, a server device, and a router. The plurality of IF cards 91 are connected to an optical fiber through a plurality of ports, and perform communication based on, for example, a 10 GBASE-LR standard.

  Each of the two switch cards 92 exchanges packets between the plurality of IF cards 91. More specifically, the switch card 92 receives a packet from the IF card 91 and outputs the packet to the IF card 91 corresponding to the destination. The two switch cards 92 are used as an active system and a standby system in preparation for a failure such as a hardware failure, for example.

  The control card 93 controls the plurality of IF cards 91 and the two switch cards 92. The control card 93 is connected to a network control device or the like, and performs processing related to the user interface, setting processing for the cards 91 and 92, information collection processing from the cards 91 and 92, and the like. The control card 93 includes a processor 930 such as a CPU (Central Processing Unit) that executes these processes, and a memory 931 that stores a program that drives the processor 930.

  FIG. 2 is a configuration diagram showing a functional configuration of the IF card 91. The IF card 91 includes a plurality of optical transceivers 910, a PHY / MAC unit 911, an input processing unit 912, an output processing unit 913, a control unit 914, and a storage unit 915.

  Each of the plurality of optical transceivers 910 converts an optical signal received from another device via an optical fiber into an electrical signal and outputs the electrical signal to the PHY / MAC unit 911. In addition, the electrical signals received from the PHY / MAC unit 911 The signal is converted into an optical signal and transmitted to another device via an optical fiber. That is, the plurality of optical transceivers 910 function as a plurality of ports # 1 to #N (N: a positive integer) for transmitting and receiving packets to and from other devices.

  The PHY / MAC unit 911 performs link establishment processing with other devices, packet distribution processing to a plurality of optical transceivers 910, and the like. The PHY / MAC unit 911 outputs a packet input from the plurality of optical transceivers 910 to the input processing unit 912 and outputs a packet input from the output processing unit 913 to the plurality of optical transceivers 910.

  The input processing unit 912 and the output processing unit 913 are logic circuits such as an FPGA (Field Programmable Gate Array) and an ASIC (Application Specific Integrated Circuit), and respectively perform ingress (INGRESS) and egress (EGRESS) packet processing. The input processing unit 912 performs bandwidth control processing for the packet input from the PHY / MAC unit 911 and outputs the packet to the switch card 92.

  The output processing unit 913 performs processing for controlling the transmission rate of the packet input from the switch card 92 and outputs the packet to the PHY / MAC unit 911. The storage unit 915 is a storage unit such as a memory, and stores various data used by the input processing unit 912 and the output processing unit 913.

  The control unit 914 communicates with the control card 93 and controls the input processing unit 912 and the output processing unit 913. The control unit 914 includes a processor such as a CPU and a memory (not shown). Examples of the processing of the control unit 914 include various setting processing of the input processing unit 912 and the output processing unit 913, and collection processing of alarms detected by the input processing unit 912 and the output processing unit 913.

  FIG. 3 shows a packet path in the packet relay apparatus. 3 also shows the configuration of the input processing unit 912 and the output processing unit 913.

  First, the packet is input to the input processing unit 912 of the IF card 91. The input processing unit 912 includes a flow determination unit 80, a bandwidth control unit 81, a distribution unit 82, a plurality of input queues 83, and an output unit 84.

  The flow determination unit 80 determines the packet traffic, that is, the flow based on the VID or MPLS label assigned to the input packet. After the determination, the flow determination unit 80 assigns, for example, a PID (Policer ID: policer identifier) corresponding to the flow of the packet to the packet. Note that the PID is stored, for example, in an in-device header attached to the packet in the packet relay device.

  The band control unit 81 includes a plurality of policers # 1 to #M (M: a positive integer) corresponding to the PID. The bandwidth control unit 81 distributes the packet to the plurality of policers # 1 to #M based on the PID assigned to the packet, for example. Therefore, for example, even when the same user's packet is input from different ports 910, the user's packet is input to the common policers # 1 to #M. The plurality of policers # 1 to #M discard packets that exceed the predetermined bandwidth so that the traffic volume of the input packets does not exceed the predetermined bandwidth.

  The policers # 1 to #M pass packets by consuming tokens supplied at a constant policing rate. If the tokens are insufficient, the policers # 1 to #M discard the packets and pass the bandwidth of the packets passing through the bandwidth control unit 81. To control. A token is an example of an allowable amount for passing a packet. Since policers # 1 to #M control the bandwidth for each user traffic, the token supply rate of each policer # 1 to #M, that is, the licing rate, is determined according to the bandwidth contracted by the user. Packets that have passed through policers # 1 to #M are input to distribution unit 82.

  The distribution unit 82 distributes the packet to a plurality of input queues 83 according to the IF card 91 that is a destination. That is, the input queue 83 is provided for each IF card 91. The plurality of input queues 83 accumulate packets until they are read by the output unit 84. The output unit 84 selects one from the plurality of input queues 83, reads a packet from the selected input queue 83, and outputs the packet to the switch unit 920 of the switch card 92. The switch unit 920 outputs the input packet to the output processing unit 913 of the IF card 91 corresponding to the destination.

  The output processing unit 913 includes a distribution unit 70, a plurality of queues 71, a read processing unit 72, and a shaper (scheduler) 73. The packet output from the switch unit 920 is input to the distribution unit 70. For example, the distribution unit 70 distributes packets to the plurality of queues 71 for each of the above-described user traffic.

  The read processing unit 72 reads packets from the plurality of queues 71 in accordance with instructions from the shaper 73. The read packet is transmitted from the port 910 to another device.

  The shaper 73 acquires packet information (packet data amount and the like) stored in the plurality of queues 71 from the distribution unit 70, and becomes a target to be read from the plurality of queues 71 based on the acquired information. The queue is instructed to the read processing unit 72. Thereby, the transmission rate for each traffic is appropriately controlled.

  FIG. 4 is a configuration diagram illustrating an example of the bandwidth control unit 81. The bandwidth control unit 81 includes a plurality of policers # 1 to #M, a token management table 20, a passage amount management table 30, a passage amount notification unit 31, a provisional passage amount management table 40, and a passage amount reception unit. 41, policer table 50, and MSB setting unit 51. The bandwidth control unit 81 controls the bandwidth of packets that pass through the policers # 1 to #M.

  Each of the plurality of policers # 1 to #M includes a policing unit 1 and a token management unit 21 that functions as the token bucket 2. FIG. 4 shows only the configuration of policer #i (i: positive integer) among the plurality of policers # 1 to #M, but other policers have the same configuration as policer #i. Have.

  The policer #i belongs to the same group as the policer #i of the other IF card 91 and performs group policing. That is, policers with the same PID among a plurality of IF cards 91 belong to the same group. Therefore, in each IF card 91, the policing unit 1 and the token management unit 21 are provided for each group. There is no limitation on the number of policers to be grouped.

  The token bucket 2 stores tokens supplied at a constant policing rate. A policing rate (= a token supply amount Tm of 1 degree / a time interval Ts during which tokens are supplied) is determined according to a bandwidth contracted by a user for input traffic. The token bucket 2 is a conceptual configuration shown as a means for managing the token accumulation amount Tc.

  The policing rate is set to the same value between policers #i belonging to the same group. That is, policers belonging to the same group have the same policing rate between the IF cards 91. When any policer #i belonging to the same group passes the packet, the tokens of all policers #i are reduced.

  Thereby, the total bandwidth of the traffic of the same user or the total bandwidth of the traffic of different users input over the policer #i of a plurality of different IF cards 91 is entirely limited.

  The token management unit 21 manages the token accumulation amount Tc and the like using the token management table 20 stored in the storage unit 915.

  FIG. 5 shows an example of the token management table 20. In the token management table 20, “maximum accumulation amount (Tmax) [Byte]”, “supply amount (Tm) [Byte]”, and “accumulation amount (Tc) [Byte]” are registered for each PID. The token management table 20 is shared between the policers # 1 to #M.

  “Accumulation amount (Tc) [Byte]” indicates the token accumulation amount Tc in the token bucket 2 in bytes, and “Maximum accumulation amount (Tmax) [Byte]” can be accumulated in the token bucket 2. The maximum amount of tokens is shown in bytes. The accumulation amount Tc is limited so as not to exceed the maximum accumulation amount. “Supply amount (Tm) [Byte]” indicates the amount Tm of tokens periodically supplied at the time interval Ts in units of bytes.

  Within the same group, the maximum accumulation amount Tmax and the supply amount Tm of tokens are common among the policers because the policing rate is common. For example, in each policer # 1 of the IF card 91 in the same group, the maximum accumulation amount Tmax and the supply amount Tm of the token are 10000 (Byte) and 3000 (Byte), respectively. The maximum token accumulation amount Tmax and supply amount Tm are set in advance from the control card 93, for example. The time interval Ts at which tokens are supplied is determined according to the policing rate registered in the policer table 50, and is common among policers in the same group.

  When the token supply timing arrives, the token management unit 21 acquires the accumulation amount Tc and the supply amount Tm from the token management table 20, and adds the supply amount Tm to the accumulation amount Tc, thereby accumulating in the token management table 20. The quantity Tc is updated.

  FIG. 6 is a flowchart illustrating an example of processing of the token management unit 21. This process is repeatedly executed at a constant cycle.

  First, the token management unit 21 determines whether or not the token supply timing has come (step St11). For example, the token management unit 21 detects the token supply timing using a built-in timer. The token supply timing arrives at each time interval Ts and is determined by the policing rate of each of the policers # 1 to #M registered in the policer table 50. This time interval Ts is calculated by dividing the supply amount Tm by the polishing rate. If the token supply timing has not arrived (No in step St11), the token management unit 21 ends the process.

  When the token supply timing has arrived (Yes in step St11), the token management unit 21 determines whether the sum of the accumulation amount Tc and the supply amount Tm is equal to or less than the maximum accumulation amount Tmax (step St12). ). If Tc + Tm ≦ Tmax (Yes in step St12), the token management unit 21 adds the supply amount Tm to the accumulation amount Tc (step St13), and ends the process.

  When Tc + Tm> Tmax is satisfied (No in step St12), the token management unit 21 sets the accumulation amount Tc as the maximum accumulation amount Tmax (step St14) and ends the process. In this way, the token management unit 21 executes processing.

  In this way, the token management unit 21 supplies tokens to the policer #i at a constant policing rate common to each group of policers #i. Further, the token is subtracted when the packet passes through any policer #i in the group.

  Referring to FIG. 4 again, the policing unit 1 is an example of a passage control unit, and determines whether or not the packet can pass based on the token, and passes or discards the packet according to the determination result. More specifically, the policing unit 1 determines whether or not the packet can be passed based on a comparison result between the token accumulation amount Tc and a predetermined threshold, and allows the packet to pass or is discarded according to the comparison result. To do. In this embodiment, the threshold value is 0, but is not limited to this.

  Therefore, the policing unit 1 allows the packet to pass when Tc> 0, and discards the packet when Tc ≦ 0. The passed packet is output to the distribution unit 82. The policing unit 1 may determine whether or not the packet can be passed according to a comparison result between the packet length (that is, the data amount) L and the token accumulation amount Tc. In this case, the policing unit 1 passes the packet when Tc ≧ L, and discards the packet when Tc <L. For this reason, the token accumulation amount Tc is always larger than 0 and does not become a negative value.

  FIG. 7 is a flowchart showing an example of processing of the policing unit 1. This process is repeatedly executed at a constant cycle.

  First, the policing unit 1 detects the presence / absence of a packet input (step St1). When no packet is input (No in step St1), the policing unit 1 ends the process. In addition, when a packet is input (Yes in step St1), the policing unit 1 detects the input packet length L (step St2). The packet length is detected using, for example, a byte counter.

  Next, the policing unit 1 determines whether or not the token accumulation amount Tc is greater than 0 (step St3). When Tc ≦ 0 (No in Step St3), the policing unit 1 discards the packet (Step St6) and ends the process. In addition, when Tc> 0 (Yes in step St3), the policing unit 1 passes the packet (step St4).

  Next, the policing unit 1 adds the packet length L to the passage amount of the policer #i registered in the passage amount management table 30 (step St5), and ends the process. In this way, the policing unit 1 executes the process.

  The passage amount notification unit 31 is an example of a passage amount management unit, and manages the data amount (bytes) of packets that have passed through the policers # 1 to #M, that is, the passage amount. The passing amount for each policer # 1 to #M is registered in the passing amount management table 30. As described above, every time a packet passes through the policer #i, the packet length L is added to the passing amount of the policer #i. Is done.

  The passing amount notifying unit 31 measures the passing amount of the packet for every fixed period by the passing amount management table 30. In this embodiment, the passage amount notification unit 31 acquires the passage amounts of the policers # 1 to #M from the passage amount management table 30 at intervals of 10 (ms). However, as described later, the setting from the control unit 914 is performed. Depending on the policer #i, it may be acquired at different time intervals for each group of policers #i.

  The passing amount notifying unit 31 notifies the band control unit 81 of the IF card 91 and the other IF card 91 of the numerical value of the upper digit of the passing amount, and the numerical value of the lower digit of the passing amount is Inherit to the passing amount measured in the period. More specifically, the passing amount notifying unit 31 notifies the band control unit 81 of the other IF card 91 not only the numerical values of all the digits of the passing amount but only the numerical values of some of the upper digits, and the remaining Are left in the passage amount management table 30.

  As a result, the amount of information to be notified is reduced without reducing the accuracy of bandwidth control. As will be described later, the passing amount notifying unit 31 acquires a bit value for 4 bits from the most significant bit (MSB) indicating the binary notation of the passing amount from the passing amount management table 30. To notify.

  The passing amount receiving unit 41 receives the numerical values transmitted from the passing amount notifying unit 31 of the IF card 91 and the band control unit 81 of the other IF card 91. The passage amount receiving unit 41 is an example of a passage amount acquisition unit, and obtains a provisional passage amount by returning the numerical value notified from the band control unit 81 of the other IF card 91 to the original digit.

  The provisional passage amount is an approximate passage amount represented by only the numerical value of the upper digit of the passage amount measured by the passage amount notification unit 31. The passage amount receiving unit 41 registers the provisional passage amount in the provisional passage amount management table 40 for each policer. As will be described later, the passage amount receiving unit 41 acquires the most significant bit of the bit string indicating the passage amount from the provisional passage amount management table 40 when obtaining the provisional passage amount.

  The token management unit 21 subtracts the #i temporary passage amount of the policer registered in the temporary passage amount management table 40 from the token accumulation amount Tc of the policer #i. As a result, the token of the policer #i is decremented every time the temporary passage amount of the packet that has passed through the policer #i or another policer #i of the same group. Therefore, the total bandwidth of traffic input to each policer #i of the plurality of IF cards 91 is limited as a whole.

  The policer table 50 is held in the storage unit 915, and the policing rate for each of the policers # 1 to #M is registered. As described above, the policing rate is common for each policer group, that is, for each PID, and is registered by the control unit 914, for example.

  The MSB setting unit 51 calculates the maximum value of the passage amount of each of the policers # 1 to #M based on the policing rate for each of the policers # 1 to #M registered in the policer table 50. The MSB setting unit 51 obtains the most significant digit of the passage amount from the maximum value of the passage amount, that is, the MSB in the case of a binary number, and registers it in the passage amount management table 30 and the provisional passage amount management table 40.

  Next, the passing amount notification process will be described. In the following description, the configuration shown in FIG. 8 is assumed.

  FIG. 8 shows an example of an interface card that constitutes a policing group. Between the IF card (# 1) 91 and the IF card (# 2) 91, policers # 1 to #M having the same PID belong to the same group. For this reason, the passing amount notifying unit 31 of the IF card (# 1) 91 transmits the numerical value of the passing amount to each passing amount receiving unit 41 of the IF card (# 1) 91 and the IF card (# 2) 91. The passing amount notifying unit 31 of the IF card (# 2) 91 also transmits the passing amount to the passing amount receiving units 41 of the IF card (# 1) 91 and the IF card (# 2) 91.

  FIG. 9 shows an example of the passing amount notification process. In this example, there is a case where the numerical value of the passage amount of policers # 1 to #M of IF card (# 2) 91 is notified to IF card (# 1) 91, but policer # 1 of IF card (# 1) 91 is notified. The same process is performed when the IF card (# 2) 91 is notified of the numerical value of the passing amount of .about. # M.

  In FIG. 9, policer table 50 of IF card (# 1) 91 and IF card (# 2) 91, passage amount management table 30 of IF card (# 1) 91, and IF card (# 2) 91 A temporary passage amount management table 40 is shown.

  In the policer table 50, common settings are registered between the IF card (# 1) 91 and the IF card (# 2) 91. In this example, the policing rate for PID = # 0 is 1 (Gb / s), the policing rate for PID = # 1 is 100 (Mb / s), and the policing rate for PID = # M is 10 (Gb / s). s).

  As described above, the policing rate is common for each policer group, that is, for each PID. For this reason, the IF card (# 1) 91 and the IF card (# 2) 91 convert the policing rate so that the passing amount of each PID measured in the other IF card (# 2, # 1) 91 is calculated. The maximum value (upper limit value) can be obtained.

  In the policer table 50 in FIG. 9, the maximum value (Byte / 10 ms) of the passage amount when the notification interval is 10 (ms) is described in a dotted frame. The maximum value of the passage amount of PID = # 0 is 1.25 (MByte / 10 ms), the maximum value of the passage amount of PID = # 1 is 0.125 (MByte / 10 ms), and the passage amount of PID = # M The maximum value is 12.5 (MByte / 10 ms). The maximum value of the passage amount is described in the policer table 50 for convenience of explanation, but it may not actually be registered in the policer table 50.

  The MSB in the passage amount management table 30 and the provisional passage amount management table 40 indicates the most significant digit when the passage amount is represented by a bit string in binary notation, and is calculated from the maximum value of the passage amount. For example, since the maximum value of the passage amount of PID = # 0 is 1.25 (MByte / 10 ms), the MSB of PID = # 0 is 21 by converting 1.25M from decimal notation to binary notation. Calculated to be a bit. In a similar manner, the MSB with PID = # 1 is calculated to be 17 bits, and the MSB with PID = # M is calculated to be 24 bits. The MSB calculation and registration in the passage amount management table 30 and the temporary passage amount management table 40 are performed by the MSB setting unit 51.

  In the passage amount management table 30, an MSB and a passage amount bit string are registered for each PID. Although a maximum 27 (bit) bit string can be registered in the passing amount management table 30, only digits less than the MSB are used. For example, the passage amount of PID = # 0 is registered as a 21-bit bit string, the passage amount of PID = # 1 is registered as a 17-bit bit string, and the passage amount of PID = # M is registered as a 24-bit bit string. Yes.

  The passing amount notifying unit 31 notifies the band control unit 81 of the IF card (# 1) 91 of a bit value corresponding to the number of digits from the MSB of the bit string indicating the binary notation of the passing amount, and the remaining bit string is transmitted. Take over to the passage amount measured in the next period. More specifically, the passing amount notifying unit 31 extracts and notifies the bit values BN # 0, BN # 1, and BN # M for 4 bits from the MSB of the bit string. The number of bits to be extracted is not limited to 4 bits.

  In this embodiment, since the bit string of the passing amount of PID = # 0 is “10000101... 1111”, “1000” for 4 bits from the 21-bit digit that is the MSB is notified as the bit value BN # 0. The Since the bit string of the passing amount of PID = # 1 is “10101100... 0001”, “1010” for 4 bits from the 17-bit digit that is the MSB is notified as the bit value BN # 1. Further, since the bit string of the passing amount of PID = # M is “11001010... 1011”, “1100” for 4 bits from the 24-bit digit that is the MSB is notified as the bit value BN # M.

  The passage amount receiving unit 41 obtains a provisional passage amount by shifting the bit values BN # 0, BN # 1, and BN # M notified from the passage amount notification unit 31 to match the MSB. For example, the passage amount receiving unit 41 obtains a provisional passage amount (bit string “11000000... 0000”) by shifting the bit value BN # M to the upper side by 24 bits. In the same manner, the passage amount receiving unit 41 shifts the bit value BN # 0 by 21 bits and shifts the bit value BN # 1 by 17 bits to obtain the provisional passage amount.

  The passage amount receiving unit 41 refers to the MSB of the temporary passage amount management table 40 to determine the number of bits to be shifted. Since the MSB is set based on the policing rate common in the same group in the IF card (# 1) 91 and the IF card (# 2), the passing amount receiving unit 41 is notified from the passing amount notifying unit 31 Based on the numerical value, the temporary passage amount can be normally obtained.

  As described above, the passing amount notifying unit 31 controls the bandwidth of the other IF card 91 by using not only the numerical values of all the digits of the passing amount, but also the numerical values of some upper digits (4 (bit) in this example). Since it can be notified to the unit 81, the amount of information to be notified for bandwidth control is reduced.

  Further, the passing amount notifying unit 31 notifies the bit value BN # i of a part of the number of digits (4 (bits in this example)) from the most significant bit (MSB) of the bit string indicating the binary notation of the passing amount. . The passing amount receiving unit 41 shifts the notified bit value BN # i for a certain number of digits to match the most significant bit.

  For this reason, according to the present embodiment, the passing amount can be notified with a smaller amount of information than when a decimal digit or a hexadecimal digit of the passing amount is notified as a bit string. However, the passage amount notification unit 31 may notify the passage amount using a bit string in decimal notation or hexadecimal notation instead of the binary notation.

  Furthermore, the passing amount notifying unit 31 is a numerical value BN of a predetermined number of digits (4 (bit) in this example) from the most significant digit (MSB) of the passing amount calculated from the maximum value of the passing amount based on the policing rate. #I is notified. The passing amount receiving unit 41 obtains a provisional passing amount by moving up the notified digit BN # i so as to match the highest digit (MSB).

  Since the passage amount notification unit 31 and the passage amount reception unit 41 can calculate the most significant digit of the passage amount based on the common policing rate, the passage amount reception unit 41 can normally obtain the provisional passage amount. Therefore, since the passing amount notifying unit 31 does not need to notify the passing amount receiving unit 41 of the highest digit, the amount of information to be notified is reduced.

  FIG. 10 is a flowchart illustrating an example of processing of the passage amount notification unit 31. This process is repeatedly executed at a constant cycle.

  First, the passing amount notifying unit 31 determines whether or not the notification timing has arrived (step St21). The passage amount notification unit 31 detects the notification timing using, for example, a built-in timer. The notification timing arrives every 10 (ms), for example, but may be different for each group as will be described later.

  If the notification timing has not arrived (No in step St21), the passing amount notification unit 31 ends the process. Further, when the notification timing has arrived (Yes in step St21), the passing amount notifying unit 31 specifies the MSB of the passing amount (step St22). In the present embodiment, the passing amount notifying unit 31 specifies the MSB from the passing amount management table 30, but, as will be described later, in the bit string indicating the binary notation of the passing amount, the most significant digit indicating “1” May be identified as the MSB.

  Next, the passing amount notifying unit 31 acquires a bit value BN # i corresponding to a predetermined number of digits from the MSB in the bit string in binary notation of the passing amount (step St23). In the present embodiment, the passing amount notifying unit 31 extracts a 4-bit bit value BN # i from the MSB from a bit string in binary notation of the passing amount.

  Next, the passing amount notifying unit 31 notifies the acquired bit value BN # i to the band control unit 81 of another IF card 91 (step St24). Next, the passing amount notifying unit 31 clears the digit of the notified bit value BN # i in the passing amount management table 30 to 0 (step St25). For this reason, the remaining bit values are not cleared but are passed on to the passage amount measured in the next period. In this way, the passing amount notifying unit 31 executes the process.

  FIG. 11 is a flowchart illustrating an example of processing of the passage amount receiving unit 41. This process is repeatedly executed at a constant cycle.

  First, the passing amount receiving unit 41 determines whether or not the bit value BN # i is notified from the passing amount notifying unit 31 of the other IF card 91 (step St31). If there is no notification (No in step St31), the passage amount receiving unit 41 ends the process.

  Next, the passage amount receiving unit 41 acquires the provisional passage amount by shifting the bit value BN # i to the higher side so as to match the MSB (step St32). Next, the passage amount receiving unit 41 registers the provisional passage amount in the provisional passage amount management table 40 (step St33).

  Next, the passage amount reception unit 41 requests the token management unit 21 to subtract the provisional passage amount from the token accumulation amount Tc (that is, Tc = Tc−temporary passage amount) (step St34). . In this way, the passage amount receiving unit 41 executes processing.

  FIG. 12 shows an example of processing of the passage amount management table 30 and the provisional passage amount management table 40. In this example, it is assumed that the passing amount of packets within a certain period of policer #M of IF card (# 2) 91 is 5000000 (Bytes).

  For this reason, the passage amount management table 30 of the IF card (# 2) 91 records a bit string “010011000100101101000000” indicating the binary notation of 5000000 (Bytes) as the passage amount of the policer #M. The passing amount notifying unit 31 extracts a bit value BN # M corresponding to a predetermined number of digits (X) from the MSB (= 24) of the bit string, and notifies the bandwidth control unit 81 of the IF card (# 1) 91. . In this example, a bit value BN # M (= “0100”) for X = 4 (bit) is notified.

  In the IF card (# 1) 91, the passage amount reception unit 41 shifts the bit value BN # M notified from the passage amount notification unit 31 of the IF card (# 1) 91 so as to match the MSB (= 24). . More specifically, the passage amount receiving unit 41 shifts the bit value BN # M to the upper side by 24 bits. That is, the passage amount receiving unit 41 returns the bit value BN # M, which is the numerical value of the higher-order digit, to the original MSB digit. The MSB is calculated from the maximum value of the passage amount based on the policing rate and set in the passage amount management table 30 and the provisional passage amount management table 40 by the MSB setting unit 51 as described above.

  In this way, the passage amount receiving unit 41 obtains the provisional passage amount and records it in the provisional passage amount management table 40. The provisional passage amount is a numerical value in which the bit values of all digits other than the MSB side bit value BN # i, which is the numerical value of the higher-order digit of the passage amount, are “0” in the passage amount bit string. An error occurs between the passage amount.

  However, since the numerical value of the lower digit of the passing amount is carried over to the passing amount measured in the next period, it is reflected in the numerical value notified to the bandwidth control unit 81 of the IF card (# 1) 91 in the next period. The More specifically, after the notification of the bit value BN # M, the passing amount notifying unit 31 of the IF card (# 1) 91 has 21 to 24 bits that are digits of the bit value BN # M in the passing amount bit string. Is cleared to 0, and the bit values of other digits are not cleared but are left as they are.

  For this reason, the bit value “11000100101101000000” of the remaining lower-order digits (1 to 20 bits) in the bit string of the passage amount is added to the passage amount measured in the next period. That is, in the next period, the passage amount starts from 805696 (Byte) (decimal notation of “11000100101101000000”) instead of 0 (Byte). For this reason, the accuracy of the band control in the present embodiment is maintained at the same level as when the passing amount itself is notified. This will be described below using simulation results.

  FIG. 13 is a graph illustrating an example of changes in the passage amount and the provisional passage amount for each period. In FIG. 13, the actual passing amount and the temporary passing amount in each period T1 to T5 are shown by a bar graph, and the cumulative value of the passing amount and the cumulative value of the temporary passing amount are shown by a line graph. Note that the actual passing amount means the data amount of the actually passed packet to which the lower digits of the passing amount in the previous period T1 to T5 are not added, and in this example, a constant value (1 (MByte)).

  Further, at the bottom of the graph, the passage amount before notification, the provisional passage amount, and the passage amount after notification in each period T1 to T5 are described in decimal numbers. Here, the passage amount after passage means the passage amount after the bit value of the MSB side to be notified (that is, X = 4 (bit)) is cleared to 0 in the bit string of passage amount.

  In the first period T1, 913504 (Bytes), which is smaller than the actual passing amount of 1000000 (Bytes), is notified and processed as a temporary passing amount.

  The passing amount in the next period T2 is 1082496 (Bytes) by adding the passing amount 82496 (Bytes) after the notification in the previous period T1 to the actual passing amount 1000000 (Bytes). In the period T2, 1048576 (Bytes) larger than the actual passing amount of 1000000 (Bytes) is notified and processed as a provisional passing amount.

  The passing amount in the next period T3 is 1033920 (Bytes) by adding 33920 (Bytes) after the notification in the previous period T2 to the actual passing amount 1000000 (Bytes). In the period T3, 913504 (Bytes), which is smaller than the actual passing amount of 1000000 (Bytes), is notified and processed as a temporary passing amount.

  The passing amount in the next period T4 becomes 1116416 (Bytes) by adding the passing amount 116416 (Bytes) after the notification in the previous period T3 to the actual passing amount 1000000 (Bytes). In the period T4, 1048576 (Bytes) larger than the actual passing amount of 1000000 (Bytes) is notified and processed as a provisional passing amount.

  The passing amount in the next period T5 is 1067840 (Bytes) by adding 67840 (Bytes) after the notification in the previous period T4 to the actual passing amount 1000000 (Bytes). In the period T5, 1048576 (Bytes) larger than the actual passing amount of 1000000 (Bytes) is notified and processed as a temporary passing amount.

  Thus, the provisional passage amount may be larger or smaller than the actual passage amount every period T1 to T5. For this reason, there is a difference between the passage amount and the temporary passage amount in each of the periods T1 to T5, but there is almost no difference between the cumulative value of the passage amount and the cumulative value of the temporary passage amount. Therefore, the accuracy of the band control in the present embodiment is maintained at the same level as when the passing amount itself is notified.

  In the present embodiment, the passing amount notifying unit 31 notifies the numerical value for a predetermined number of digits from the most significant digit of the passing amount calculated from the maximum value of the passing amount based on the policing rate, but is not limited thereto. The passing amount notifying unit 31 may notify a numerical value for a predetermined number of digits from the most significant digit of the passing amount and the most significant digit of the passing amount. In this case, the passage amount receiving unit 41 obtains a provisional passage amount by moving up the notified number of digits corresponding to the predetermined number of digits to match the notified highest digit. An embodiment in this case will be described below.

  FIG. 14 shows another example of processing of the passage amount management table 30 and the provisional passage amount management table 40. In this example, it is assumed that the passing amount of packets within a certain period of policer #M of IF card (# 2) 91 is 5000000 (Bytes).

  For this reason, the passage amount management table 30 of the IF card (# 2) 91 records a bit string “010011000100101101000000” indicating the binary notation of 5000000 (Bytes) as the passage amount of the policer #M. The passing amount notifying unit 31 extracts a bit value BN # M corresponding to a predetermined number of digits (X) from the most significant digit (Y) in which the bit value is “1” in the bit string, and the IF card ( # 1) Notify the band control unit 81 of 91.

  In this example, the most significant digit having a bit value “1” is 23 (Y = 23), and the number of digits X to be notified is 4 (bits). Therefore, the passing amount notifying unit 31 notifies the bit value BN # M (= “1001”) of 20 to 23 bits in the bit string of the passing amount. The passing amount notifying unit 31 also notifies the highest digit Y = 23 (bit) together with the bit value BN # M.

  After the notification of the bit value BN # M, the passing amount notifying unit 31 clears the bit values of the 20 to 23 bits, which are the digits of the bit value BN # M, from the bit string of the passing amount to 0, and bits of other digits Leave the value as it is without clearing it. For this reason, the bit value “1000100101101000000” of the remaining lower-order digits (1 to 19 bits) in the bit string of the passage amount is added to the passage amount measured in the next period.

  That is, this bit value is carried over to the passage amount measured in the next period. Therefore, the accuracy of the bandwidth control in the present embodiment is maintained at the same level as when the passing amount itself is notified, as in the above-described embodiment.

  Further, in the IF card (# 1) 91, the passage amount reception unit 41 receives the bit value BN # M notified from the passage amount notification unit 31 of the IF card (# 2) 91 in the same manner as this. Shift to match the upper digit Y = 23 bits. More specifically, the passage amount receiving unit 41 shifts the bit value BN # M to the upper side by 23 bits. In this way, the passage amount receiving unit 41 obtains the provisional passage amount and records it in the provisional passage amount management table 40.

  In this way, in this embodiment, the passing amount notifying unit 31 omits the notification of the bit value “0” of the 24-bit digit of the bit string of the passing amount, and notifies the bit value BN # M of the 20-bit digit instead. To do. That is, the passing amount notifying unit 31 does not notify the bit value “0” of the upper digit of the bit string in vain, but instead notifies the bit value of the lower digit. Thereby, the accuracy of the provisional passage amount is improved.

  For example, when this embodiment is compared with the previous embodiment shown in FIG. 12, the provisional passage amount is 4718592 (bytes) in decimal notation in this embodiment, whereas the provisional passage is in the previous embodiment. The amount is 4194304 (Byte) in decimal notation. For this reason, the temporary passage amount of the present embodiment is closer to the passing amount of 5000000 (Bytes) than the temporary passage amount of the previous embodiment.

  In the embodiments described so far, the number of digits of the bit value BN # M to be notified (X (bit)) and the notification time interval, that is, the period for measuring the passage amount may be different for each policer group. .

  FIG. 15 shows another example of the passing amount notification process. In this example, the number of digits of the bit value BN # M to be notified (X (bit)) and the notification time interval (hereinafter referred to as “notification interval”) are for each group of policers # 0, # 1, and #M. Is different.

  Therefore, a common notification interval is set for each group in each policer table 50 of the IF card (# 1) 91 and the IF card (# 2) 91. The passing amount notifying unit 31 of the IF card (# 2) 91 performs notification processing at a notification interval for each of the policers # 1 to #M set in the policer table 50. The notification interval is set by the control unit 914, for example.

  In this example, the notification interval of policers # 0 and # 1 is 10 (ms) as in the above example, and the notification interval of policer #M is 1 (ms). The policer #M has a policing rate of 10 (Gb / s), which is 1.25 (Byte / ms) when converted into a data transmission amount per 1 ms. Therefore, 21 bits are set in the passing amount management table 30 of the IF card (# 2) 91 as the MSB of PID # M.

  Thus, by making the notification interval of the group of policer #M with the highest police rate shorter than the groups of other policers # 0 and # 1, the accuracy of policing of the policer #M can be improved.

  In addition, in the passage amount management table 30 of the IF card (# 2) 91 and the temporary passage amount management table 40 of the IF card (# 1) 91, a common number of digits X (bit) is provided for each of the policers # 1 to #M. Has been set (see symbol W). The passing amount notifying unit 31 of the IF card (# 2) 91 notifies bit values BN # 0, # 1, #M for X (bit) set in the passing amount management table 30.

  On the other hand, the passage amount receiving unit 41 of the IF card (# 1) 91 receives the bit values BN # 0, # 1, #M of X (bit) set in the temporary passage amount management table 40. Thereby, the bit values BN # 0, # 1, #M of X (bit) are normally transmitted and received between the IF card (# 1) 91 and the IF card (# 2) 91. Note that X (bit) is set by the control unit 914, for example.

  In this example, X (bit) of policers # 0 and #M is 4 (bits), and X (bit) of policer # 1 is 8 (bits). For this reason, the policing accuracy of the policer # 1 is higher than that of the policer # 0 having the same notification interval. Unlike this example, the notification interval of the group of policer #M having the highest policing rate is set to the same value (10 ms) as the groups of other policers # 0 and # 1, and X (bit) of policer #M is set. May be set to a value larger than the other policers # 0 and # 1, thereby improving the policing accuracy of the policer #M.

  As described above, in this embodiment, the number of digits (X (bit)) of the higher-order digits notified to the other IF card 91 or the notification interval, that is, the measurement period of the passage amount is policer # 0, # 1, Different for each #M group. Therefore, the policing accuracy can be adjusted for each group of policers # 0, # 1, and #M.

  Next, effects of the above-described embodiment will be described. In the following description, an example is given in which group policing is performed between policer #M of IF card (# 1) 91 and IF card (# 2) 91.

  FIG. 16 shows an example of bandwidth control. Each policer #M of the IF card (# 1) 91 and the IF card (# 2) 91 limits the passband of the packet with a policing rate of 100 (Gbps) in total. Here, the input rates of the policer #M packets of the IF card (# 1) 91 and IF card (# 2) 91 are 100 (Gbps) and 50 (Gbps), respectively.

  Packets output from the policers #M of the IF card (# 1) 91 and the IF card (# 2) 91 are input to the output-side IF card (# 3) 91 via the switch card (SW) 92. The The IF card (# 3) 91 transmits a packet to another device via a 100 GbE (Gigabit Ethernet) communication line.

  As an example, the output rate of packets of each policer #M of the IF card (# 1) 91 and the IF card (# 2) 91 is determined so that the passing rates are equal. For this reason, the expected value of the output rate of each policer #M packet is a value obtained by assigning the policing rate according to the ratio of the input rates.

  Sr = Pr × (Nr / ΣNr) (1)

  More specifically, when the input rate is Nr and the policing rate is Pr, the expected value Sr of the output rate is calculated by the above equation (1). Here, ΣNr is the total input rate of each policer #M.

  Therefore, the expected value of the output rate of the policer #M packet of the IF card (# 1) 91 is 100 × 100 / (100 + 50) = 66.6 (Gbps), and the policer #M of the IF card (# 2) 91 The expected value of the output rate of the packet is 100 × 50 / (100 + 50) = 33.3 (Gbps). At this time, the passage rate of each policer #M is equal to 66.6 (%). As a result, packets are input to the IF card (# 3) 91 on the output side at a total input rate of about 100 (Gbps).

  Note that the bandwidth control is not limited to the method of making the passing rate fair between the policers #M in the same group as described above, and a method of making the packet passing amount fair is also used. In this case, each policer #M of the IF card (# 1) 91 and the IF card (# 2) 91 outputs packets to the switch card 92 evenly at an output rate of 50 (Gbps) as an expected value. Thus, packets are input to the output-side IF card (# 3) 91 at a total input rate of 100 (Gbps).

  Next, the simulation result of the output rate of each policer #M of the IF card (# 1) 91 and the IF card (# 2) 91 in the bandwidth control shown in FIG. 16 will be described.

  FIG. 17A is a graph showing the simulation result of the output rate in the comparative example. In FIG. 17A, the horizontal axis represents elapsed time (ms), and the vertical axis represents output rate (Gbps). In the comparative example, the passing amount notifying unit 31 of the IF card (# 1) 91 notifies the passing amount receiving unit 41 of the IF card (# 2) 91 of all of the 27-bit bit string indicating the binary notation of the passing amount. To do.

  As shown in FIG. 17A, the output rate of policer #M of IF card (# 1) 91 is approximately 66.6 (Gbps), and the output rate of policer #M of IF card (# 2) 91 Is about 33.3 (Gbps). Therefore, it can be said that the output rates of the policers #M of the IF card (# 1) 91 and the IF card (# 2) 91 are as expected.

  On the other hand, FIG. 17B is a graph showing a simulation result of the output rate in the above-described embodiment. In FIG. 17B, the horizontal axis indicates elapsed time (ms), and the vertical axis indicates output rate (Gbps). In the present embodiment, the passing amount notifying unit 31 of the IF card (# 1) 91 sends the passing amount receiving unit 41 of the IF card (# 2) 91 to the MSB side of the bit string indicating the binary notation of the passing amount. A bit value BN # M of X = 4 (bit) is notified.

  As shown in FIG. 17B, the output rate of the policer #M of the IF card (# 1) 91 is maintained at about 66.6 (Gbps) although the degree of fluctuation is larger than that of the comparative example. The output rate of the policer #M of the IF card (# 2) 91 is about 33.3 (Gbps) although the degree of fluctuation is larger than that of the comparative example. Therefore, it can be said that the output rates of the policers #M of the IF card (# 1) 91 and the IF card (# 2) 91 are as expected as in the comparative example.

  Thus, according to the present embodiment, the information amount of the passing amount notified from the IF card (# 1) 91 to the IF card (# 2) 91 is about 1/7 (= 4 (bit) / 27 (bit). )) And the accuracy of band control (policing) is maintained at the same level as in the comparative example that notifies the passing amount itself.

  The token bucket method described above imposes a limit on the average packet transfer rate while allowing a certain degree of burstiness to the packet input rate. For this reason, it is important that the accuracy required for policing is obtained from a long-term viewpoint (macro viewpoint) rather than a short-term viewpoint (micro viewpoint). Therefore, the advantage of reducing the amount of information to be notified while maintaining the accuracy of the macro viewpoint even if the accuracy of the micro viewpoint decreases (see FIG. 13) is desirable for group policing.

  As described above, the packet relay apparatus according to the embodiment includes the plurality of band control units 81 that respectively control the band of the packet that passes. Each of the plurality of bandwidth control units 81 includes a policing unit 1, a passage amount notification unit 31, a passage amount reception unit 41, and a token management unit 21.

  The policing unit 1 determines whether or not a packet can be passed based on a token that is supplied at a constant policing rate and is subtracted when the packet passes, and passes or discards the packet according to the determination result. The passing amount notifying unit 31 measures the passing amount of the packet for every fixed period, notifies the other band control unit 81 of the numerical value of the upper digit of the passing amount, and the numerical value of the lower digit of the passing amount. To the passage amount to be measured in the next period.

  The passing amount receiving unit 41 obtains a provisional passing amount by returning the numerical value of the higher-order digit notified from the other band control unit 81 to the digit. The token management unit 21 subtracts the temporary passage amount from the token.

  According to the above configuration, the passing amount notifying unit 31 can notify the other band control unit 81 not only the numerical values of all the digits of the passing amount but also the numerical values of some of the upper digits. The amount of information notified for control is reduced.

  The passing amount notifying unit 31 takes over the numerical value of the lower digit of the passing amount as the passing amount measured in the next period. For this reason, the numerical value of the lower digit of the passage amount is reflected in the numerical value notified to the other bandwidth control unit 81 in the next period. Therefore, the accuracy of the bandwidth control is maintained at the same level as when the passing amount itself is notified.

  Therefore, according to the packet relay apparatus according to the present embodiment, it is possible to perform bandwidth control with a reduced amount of information to be notified.

In addition, the bandwidth control method according to the embodiment is a method in which the bandwidth control units 81 respectively execute the following steps in the method of controlling the bandwidths of packets passing through the bandwidth control portions 81, respectively.
Step (1): It is determined whether or not a packet can be passed based on a token that is supplied at a constant policing rate and is subtracted when the packet passes, and the packet is allowed to pass or discarded according to the determination result.
Step (2): The amount of packet passing is measured at regular intervals.
Step (3): The other band control unit 81 is notified of the numerical value of the upper digit of the passing amount.
Step (4): The numerical value of the lower digit of the passage amount is taken over by the passage amount measured in the next period.
Step (5): The provisional passage amount is obtained by returning the numerical value of the upper digit notified from the other bandwidth control unit to the digit.
Step (6): The temporary passage amount is subtracted from the token.

  Since the bandwidth control method according to the embodiment includes the same configuration as that of the above-described packet relay device, the same effects as the above-described contents are obtained.

  The above-described embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

In addition, the following additional notes are disclosed regarding the above description.
(Supplementary Note 1) In a packet relay device having a plurality of bandwidth control units that respectively control the bandwidths of packets passing therethrough,
Each of the plurality of bandwidth control units is
A passage control unit that determines whether or not a packet can pass based on a passage allowance that is supplied at a constant rate and is subtracted by the passage of the packet;
Measure the amount of packets passing every fixed period, and notify the other bandwidth control unit of the plurality of bandwidth control units of the numerical value of the higher-order digit of the passage amount, A passing amount management unit that takes over the numerical value of the digit to the passing amount to be measured in the next period;
A passage amount acquisition unit that obtains a provisional passage amount by returning the numerical value of the upper digit notified from the other bandwidth control unit to the digit; and
A packet relay apparatus, comprising: a passage allowance management unit that subtracts the provisional passage amount from the passage allowance.
(Additional remark 2) The said passage amount management part is a value for the predetermined number of digits from the most significant digit of the passage amount calculated from the maximum value of the passage amount based on the constant rate. Notify
The passage amount acquisition unit obtains the provisional passage amount by moving up the numerical digits for the predetermined number of digits notified from the other band control unit so as to match the highest digit of the passage amount. The packet relay device according to appendix 1, wherein:
(Supplementary Note 3) The passing amount management unit notifies the other band control unit of a numerical value for a predetermined number of digits from the most significant digit of the passing amount and the most significant digit of the passing amount,
The passing amount acquisition unit moves up the numerical digits for the predetermined number of digits notified from the other band control unit so as to match the highest digit notified from the other band control unit. The packet relay apparatus according to appendix 1, wherein the provisional passage amount is obtained by the following.
(Supplementary Note 4) The passing amount management unit notifies a bit value corresponding to the number of digits from the most significant bit of the bit string indicating the binary notation of the passing amount, and measures the rest of the bit string in the next period. Taking over the passing amount to
The passage amount acquisition unit obtains the provisional passage amount by shifting a bit value corresponding to the number of digits notified from the other band control unit to match the most significant bit. The packet relay device according to any one of appendices 1 to 3.
(Supplementary Note 5) The passage control unit and the allowable passage amount management unit are provided for each group in which the constant rate is common among the plurality of band control units,
The packet relay according to any one of appendices 1 to 4, wherein the passing amount management unit differs in the number of digits of the higher-order digit notified to the other bandwidth control unit for each group. apparatus.
(Additional remark 6) The said passage control part and the said passage allowable amount management part are provided for every group in which the said fixed rate is common among these band control parts,
6. The packet relay device according to any one of appendices 1 to 5, wherein the passage amount management unit is different in the certain period for each group.
(Supplementary note 7) In a bandwidth control method for controlling the bandwidth of a packet passing through a plurality of bandwidth controllers,
Each of the plurality of bandwidth control units is
Determine whether or not a packet can pass based on an allowable amount of passage that is supplied at a constant rate and subtracted when the packet passes, and pass or discard the packet according to the determination result;
Measure the amount of packets passing every fixed period,
Among the plurality of band control units, notify the other band control unit of the numerical value of the upper digit of the passing amount,
Passing the numerical value of the lower digit of the passing amount to the passing amount measured in the next period,
By obtaining the numerical value of the higher-order digit notified from the other bandwidth control unit to obtain the provisional passage amount,
A band control method characterized by subtracting the temporary passage amount from the allowable passage amount.
(Appendix 8) Notifying the other band control unit of a numerical value for a predetermined number of digits from the most significant digit of the passing amount calculated from the maximum value of the passing amount based on the constant rate,
Supplementary note 7 wherein the provisional passage amount is obtained by moving up the numerical digits corresponding to the predetermined number of digits notified from the other bandwidth control unit so as to match the highest digit of the passage amount. The bandwidth control method described in 1.
(Appendix 9) Notifying the other band control unit of a numerical value for a predetermined number of digits from the most significant digit of the passing amount and the most significant digit of the passing amount,
The provisional passage amount is obtained by moving up the numerical digits for the predetermined number of digits notified from the other band control unit so as to be matched with the most significant digit notified from the other band control unit. The bandwidth control method according to appendix 7, characterized by:
(Supplementary note 10) Notifying the bit value for a part of the number of digits from the most significant bit of the bit string indicating the binary notation of the passing amount, and taking over the remaining bit string to the passing amount measured in the next period,
Any one of appendixes 7 to 9, wherein the provisional passage amount is obtained by shifting the bit value for the number of digits notified from the other band control unit so as to match the most significant bit. The band control method according to claim 1.
(Supplementary Note 11) The determination of whether or not the packet is allowed to pass and the subtraction of the provisional passage amount from the passage allowance amount are performed for each group in which the constant rate is common among the plurality of band control units,
11. The bandwidth control method according to any one of appendixes 7 to 10, wherein the number of digits of the higher-order digits notified to the other bandwidth control unit is different for each group.
(Supplementary Note 12) The determination of whether or not the packet is allowed to pass and the subtraction of the provisional passage amount from the passage allowance amount are performed for each group in which the constant rate is common among the plurality of band control units,
11. The bandwidth control method according to any one of appendices 7 to 10, wherein the certain period is different for each group.

DESCRIPTION OF SYMBOLS 1 Policing part 20 Token management table 21 Token management part 30 Passage amount notification part 31 Passage amount management table 40 Temporary passage amount management table 41 Passage amount reception part

Claims (7)

In a packet relay device having a plurality of bandwidth control units that respectively control the bandwidth of packets passing therethrough,
Each of the plurality of bandwidth control units is
A passage control unit that determines whether or not a packet can pass based on a passage allowance that is supplied at a constant rate and is subtracted by the passage of the packet, and that passes or discards the packet according to the determination result;
Measure the amount of packets passing every fixed period, and notify the other bandwidth control unit of the plurality of bandwidth control units of the numerical value of the higher-order digit of the passage amount, A passing amount management unit that takes over the numerical value of the digit to the passing amount to be measured in the next period;
A passage amount acquisition unit that obtains a provisional passage amount by returning the numerical value of the upper digit notified from the other bandwidth control unit to the digit; and
A packet relay apparatus, comprising: a passage allowance management unit that subtracts the provisional passage amount from the passage allowance. The passing amount management unit notifies the other band control unit of a numerical value for a predetermined number of digits from the most significant digit of the passing amount calculated from the maximum value of the passing amount based on the constant rate,
The passage amount acquisition unit obtains the provisional passage amount by moving up the numerical digits for the predetermined number of digits notified from the other band control unit so as to match the highest digit of the passage amount. The packet relay device according to claim 1. The passing amount management unit notifies the other band control unit of a numerical value for a predetermined number of digits from the most significant digit of the passing amount and the most significant digit of the passing amount,
The passing amount acquisition unit moves up the numerical digits for the predetermined number of digits notified from the other band control unit so as to match the highest digit notified from the other band control unit. The packet relay apparatus according to claim 1, wherein the provisional passage amount is obtained by: The passing amount management unit notifies the bit value of a part of the number of digits from the most significant bit of the bit string indicating the binary notation of the passing amount, and measures the remaining amount of the bit string in the next period To take over
The passage amount acquisition unit obtains the provisional passage amount by shifting a bit value corresponding to the number of digits notified from the other band control unit to match the most significant bit. The packet relay device according to any one of claims 1 to 3. The passage control unit and the allowable passage amount management unit are provided for each group in which the constant rate is common among the plurality of band control units,
5. The packet relay device according to claim 1, wherein the number of digits of the higher-order digits notified to the other bandwidth control unit is different for each group. The passage control unit and the allowable passage amount management unit are provided for each group in which the constant rate is common among the plurality of band control units,
The packet relay device according to claim 1, wherein the certain period is different for each group. In a bandwidth control method for controlling the bandwidth of each packet passing through a plurality of bandwidth controllers,
Each of the plurality of bandwidth control units is
Determine whether or not a packet can pass based on an allowable amount of passage that is supplied at a constant rate and subtracted when the packet passes, and pass or discard the packet according to the determination result;
Measure the amount of packets passing every fixed period,
Among the plurality of band control units, notify the other band control unit of the numerical value of the upper digit of the passing amount,
Passing the numerical value of the lower digit of the passing amount to the passing amount measured in the next period,
By obtaining the numerical value of the higher-order digit notified from the other bandwidth control unit to obtain the provisional passage amount,
A band control method characterized by subtracting the temporary passage amount from the allowable passage amount.

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